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Day: 20130103

Jan. 2, 2013 — You’re standing in line somewhere and you decide to open a pack of gum. Do you share a piece with the coworker standing to one side of you, or with the stranger on the other?

This is an infant bonobo feeding on papaya. (Credit: Jingzhi Tan)

Most humans would choose the person they know first, if they shared at all.

But bonobos, those notoriously frisky, ardently social great apes of the Congo, prefer to share with a stranger before sharing with an animal they know. In fact, a bonobo will invite a stranger to share a snack while leaving an acquaintance watching helplessly from behind a barrier.

“It seems kind of crazy to us, but bonobos prefer to share with strangers,” said Brian Hare, a professor of evolutionary anthropology at Duke University. “They’re trying to extend their social network.” And they apparently value that more than maintaining the friendships they already have.

To measure this willingness to share, Hare and graduate student Jingzhi Tan ran a series of experiments with bonobos living in the Lola ya Bonobo sanctuary in Kinshasa, Democratic Republic of Congo. The experiments involved piles of food and enclosures that the test subjects were able to unlock and open. Tan and Hare describe their work in a paper in the Jan. 2, 2013 edition of PLOS ONE.

In the first series of experiments, a pile of food was placed in a central enclosure flanked by two enclosures, each of them holding another animal. The test subject had the knowledge and ability to open a door to either of the other chambers, or both. On one side was a bonobo they knew from their group (not necessarily a friend or family member) and in the other was a bonobo they had never really met, but had only seen at a distance.

Upon entering the chamber with the food, the test subjects could easily just sit down and consume it all themselves, or they could let in one or both of the other animals to share.

Nine of the 14 animals who went through this test released the stranger first. Two preferred their groupmates. Three showed no particular preference in repeated trials. The third animal was often let in on the treat as well, but more often it was the stranger, not the test subject, who opened the door for them.

Tan said that by letting the third animal into the enclosure, the stranger voluntarily outnumbered himself or herself with two bonobos who knew each other, which a chimpanzee would never do. In 51 trials of the experiment, there was never any aggression shown, although there was quite a bit of typical bonobo genital rubbing between the strangers.

To isolate how much motivation the animals receive from social interaction, the researchers ran a second set of experiments in which the subject animal wouldn’t receive any social contact with another animal. In the first of these experiments, the subjects couldn’t get any food for themselves regardless of whether they chose to open the door to allow the other animal to get some food. Nine out of ten animals shared with the stranger at least once.

In the final experiment without social contact, the subject animal was given access to the food in such a way that opening the door to share with the other animal would cost them some food. But they still wouldn’t have any social contact as a reward. In this instance, the animals chose not to share. “If they’re not going to see a social benefit, they won’t share,” Hare said.

This second test is similar to something called the dictator game in which humans are given the chance to share cash with a stranger, Hare said. Most people will share anonymously, but they share even more when they aren’t anonymous. Bonobos won’t share at all in the anonymous condition if it costs them food.

“They care about others,” Hare said, but only in a sort of selfish way. “They’ll share when it’s a low-cost/low-benefit kind of situation. But when it’s a no-benefit situation, they won’t share. That’s different from a human playing the dictator game. You really have to care about others to give anonymously.”

The findings, which Hare calls “one of the crazier things we’ve found” in more than a decade of bonobo research, form yet another distinction between bonobos and chimpanzees, our two closest relatives. “Chimps can’t do these tests, they’d be all over each other.”

The work was funded by the National Science Foundation and the European Research Council.

Jan. 2, 2013 — A new study led by North Carolina researchers has found that when it comes to weight- and fat loss, aerobic training is better than resistance training. The study is believed to the largest randomized trial to directly compare changes in body composition induced by comparable amounts of time spent doing aerobic and resistant training, or both in combination, among previously inactive overweight or obese non-diabetic adults.

The study is entitled “Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults”. It is published in the December 2012 edition of the Journal of Applied Physiology published by the American Physiological Society.

Methodology

A total of 234 previously sedentary overweight or obese males and females, age 18-70 years of age, were enrolled in one of three eight-month supervised protocols: aerobic training (AT), resistance training (RT), or a combination (AT/RT). Of the total, 119 participants completed the trials and had complete data for the variables of interest in the article.

Those assigned to aerobic training exercised vigorously, at about 70-85% of maximum heart rate. They exercise approximately 45 minutes three days per week throughout the study period.

Individuals assigned to resistance training also exercised three days a week, completing three sets of 8-12 reps on eight resistance machines that targeted all major muscle groups. Resistance was increased throughout the study to maintain a steady level of challenge as the participants gained strength.

Individuals who were assigned to AT/RT performed all the exercises assigned to both AT and RT groups. At the end of study each enrollee was assessed for weight, body composition, waist circumference, cardiopulmonary fitness and strength compared to their baseline.

Key Findings and Conclusions

The researchers found:

• The groups assigned to aerobic training and aerobic plus resistance training lost more weight than those that did resistance training only. In fact, those who did resistance training only actually gained weight due to an increase in lean body mass.

• Fat mass and waist circumference significantly decreased in the AT and AT/RT groups, but were not altered in RT. However, measures of lean body mass significantly increased in RT and AT/RT, but not in AT. The finding suggest that aerobic exercise is more effective in reducing these measures.

• Lean body mass increased with both RT and AT/RT, but not AT. Having the benefit to of both modes of exercise allowed AT/RT to decrease body fat percent significantly more than either AT or RT due to decreased fat mass combined with increased lean body mass.

Importance of the Findings

According to Leslie H. Willis, an exercise physiologist at Duke University Medical Center and the study’s lead author, “Given our observations, it may be time to seriously reconsider the conventional wisdom that resistance training alone can lead to weight and fat loss.”

Willis added, “If increasing muscle mass and strength is a goal, then resistance training is required. However, the majority of Americans could experience health benefits due to weight and fat loss. The best option in that case, given limited time for exercise, is to focus on aerobic training. When you lose fat, it is likely you are losing visceral fat, which is known to be associated with cardiovascular and other health benefits.”

In addition to Leslie Willis, the study was conducted by Cris A. Slentz, Lori A. Bateman, Lucy W. Piner, Connie W. Bales and William E. Kraus of the Duke University Medical Center; and Joseph A Hourmard and A. Tamlyn Shields of East Carolina University.

Jan. 2, 2013 — Today, mothers of newborns find themselves confronting a common dilemma: Should they let their babies “cry it out” when they wake up at night? Or should they rush to comfort their crying little one?

In fact, waking up in the middle of the night is the most common concern that parents of infants report to pediatricians. Now, a new study from Temple psychology professor Marsha Weinraub gives parents some scientific facts to help with that decision.

The study, published in Developmental Psychology, supports the idea that a majority of infants are best left to self-soothe and fall back to sleep on their own.

“By six months of age, most babies sleep through the night, awakening their mothers only about once per week. However, not all children follow this pattern of development,” said Weinraub, an expert on child development and parent-child relationships.

For the study, Weinraub and her colleagues measured patterns of nighttime sleep awakenings in infants ages six to 36 months. Her findings revealed two groups: sleepers and transitional sleepers.

“If you measure them while they are sleeping, all babies — like all adults — move through a sleep cycle every 1 1/2 to 2 hours where they wake up and then return to sleep,” said Weinraub. “Some of them do cry and call out when they awaken, and that is called ‘not sleeping through the night.'”

For the study, Weinraub’s team asked parents of more than 1,200 infants to report on their child’s awakenings at 6, 15, 24 and 36 months. They found that by six months of age, 66 percent of babies — the sleepers — did not awaken, or awoke just once per week, following a flat trajectory as they grew. But a full 33 percent woke up seven nights per week at six months, dropping to two nights by 15 months and to one night per week by 24 months.

Of the babies that awoke, the majority were boys. These transitional sleepers also tended to score higher on an assessment of difficult temperament which identified traits such as irritability and distractibility. And, these babies were more likely to be breastfed. Mothers of these babies were more likely to be depressed and have greater maternal sensitivity.

The findings suggest a couple of things, said Weinraub. One is that genetic or constitutional factors such as those that might be reflected in difficult temperaments appear implicated in early sleep problems. “Families who are seeing sleep problems persist past 18 months should seek advice,” Weinraub said.

Another takeaway is that it is important for babies to learn how to fall asleep on their own. “When mothers tune in to these night time awakenings and/or if a baby is in the habit of falling asleep during breastfeeding, then he or she may not be learning to how to self-soothe, something that is critical for regular sleep,” she said.

According to Weinraub, the mechanism by which maternal depression is connected to infant awakenings is an area that would benefit from further research. On the one hand, Weinraub said, it’s possible that mothers who are depressed at six and 36 months may have been depressed during pregnancy and that this prenatal depression could have affected neural development and sleep awakenings. At the same time, it’s important to recognize that sleep deprivation can, of course, exacerbate maternal depression, she said.

“Because the mothers in our study described infants with many awakenings per week as creating problems for themselves and other family members, parents might be encouraged to establish more nuanced and carefully targeted routines to help babies with self-soothing and to seek occasional respite,” said Weinraub.

“The best advice is to put infants to bed at a regular time every night, allow them to fall asleep on their own and resist the urge to respond right away to awakenings.”

Jan. 2, 2013 — Infants who have started crawling wake up more often at night compared to the period before the crawling, reveals a new study by Dr. Dina Cohen of the University of Haifa’s Department of Counseling and Human Development.

The doctoral study, conducted under the supervision of Prof. Anat Scher, observed 28 healthy babies who were developing normally, examining them once every two to three weeks. Their motor development and sleeping habits were monitored from age 4-5 months and continued until age 11 months. Their sleep patterns were measured by a device called an ActiGraph that provides objective evaluations of sleep patterns, taken together with parental reports from diaries and questionnaires. The infants’ crawling development and progress was observed and videoed by the researcher.

The study showed that the average age for the babies to begin crawling was 7 months, and that this was accompanied by an increase in the number of times they woke up at night, from an average of 1.55 times per night to 1.98 times (based on the ActiGraph measurements). The incidents of wakefulness also lasted longer, about 10 minutes on average, as per parental reports.

The study also found that the scope and complexity of the changes — which included waking more frequently and moving around a lot during asleep — were more pronounced among those who started crawling earlier. By contrast, those who started to crawl later demonstrated only one change: waking up more frequently.

The good news for parents: Within three months from the day crawling begins, the baby will generally return to the sleep patterns from before acquiring the new motor skill.

According to Dr. Cohen, there are a number of reasons why starting to crawl and wakefulness could be linked. “It is possible that crawling, which involves a vast range of changes and psychological reorganization in the babies’ development, increases their level of arousal, influences their ability to regulate themselves and causes a period of temporary instability that expresses itself in waking up more frequently,” she suggests.

Increased restlessness in babies who crawl early, she says, could be attributed to the baby’s expressing fears of being physically distanced from the mother before fully developing the psychological mechanisms to cope with separation effectively. “This fear is likely to be expressed in sleep interruptions during the night,” she explained.

“With ongoing monitoring of babies’ development, we can demonstrate that the increased awakenings are a temporary short-term phenomenon, which occurs as part of a wider process of the baby’s gradually improving ability to regulate states of sleep and wakefulness,” adds Dr. Cohen.

Jan. 2, 2013 — Newborns are much more attuned to the sounds of their native language than first thought. In fact, these linguistic whizzes can up pick on distinctive sounds of their mother tongue while in utero, a new study has concluded.

Research led by Christine Moon, a professor of psychology at Pacific Lutheran University, shows that infants, only hours old showed marked interest for the vowels of a language that was not their mother tongue.

“We have known for over 30 years that we begin learning prenatally about voices by listening to the sound of our mother talking,” Moon said. “This is the first study that shows we learn about the particular speech sounds of our mother’s language before we are born.”

Before the study, the general consensus was that infants learned about the small parts of speech, the vowels and the consonants, postnatally. Moon added. “This study moves the measurable result of experience with individual speech sounds from six months of age to before birth,” she said. The findings will be published in Acta Paediatricain late December.

For the study Moon tested newborn infants shortly after birth while still in the hospital in two different locations: Madigan Army Medical Center in Tacoma, Wash., and in the Astrid Lindgren Children’s Hospital in Stockholm. Infants heard either Swedish or English vowels and they could control how many times they heard the vowels by sucking on a pacifier connected to a computer.

Co-authors for the study were. Hugo Lagercrantz, a professor at the Karolinska Institute in Sweden as well as a member of the Nobel Assembly, and Patricia Kuhl, Endowed Chair for the Bezos Family Foundation for Early Childhood Learning and Co-Director of the University of Washington’s Institute for Learning and Brain Sciences.

The study tested newborns on two sets of vowel sounds — 17 native language sounds and 17 foreign language sounds, said Kuhl. The researchers tested the babies’ interest in the vowel sounds based on how long and often they sucked on a pacifier. Half of the infants heard their native language vowels, and the other half heard the foreign vowels. “Each suck will produce a vowel until the infant pauses, and then the new suck will produce the next vowel sound,” said Kuhl.

In both countries, the babies listening to the foreign vowels sucked more, than those listening to their native tongue regardless of how much postnatal experience they had. This indicated to researchers that they were learning the vowel sounds in utero.

“These little ones had been listening to their mother’s voice in the womb, and particularly her vowels for ten weeks. The mother has first dibs on influencing the child’s brain,” said Kuhl. “At birth, they are apparently ready for something novel.”

While other studies have focused on prenatal learning of sentences or phrases, this is the first study to show learning of small parts of speech that are not easily recognized by melody, rhythm or loudness. Forty infants were tested in Tacoma and another 40 in Sweden. They ranged in age from 7 to 75 hours after birth.

Vowel sounds were chosen for the study because they are prominent, and the researchers thought they might be noticeable in the mother’s ongoing speech, even against the noisy background sounds of the womb.

The study shows that the newborn has the capacity to learn and remember elementary sounds of their language from their mother during the last 10 weeks of pregnancy (the sensory and brain mechanisms for hearing are intact at 30 weeks of gestational age).

“This is a stunning finding,” said Kuhl. “We thought infants were ‘born learning’ but now we know they learn even earlier. They are not phonetically naïve at birth.”

Prior to the kinds of studies like this one, , it was assumed that newborns were “blank slates,” added Lagercrantz. He said that although it’s been shown that infants seem to be attuned to sounds of their mother tongue, this same effect now seems to occur before birth. This surprised him.

“Previous studies indicate that the fetus seems to remember musical rhythms,” he said. “They now seem to be able to learn language partially.”

Kuhl added that infants are the best learners on the planet and while understanding a child’s brain capacity is important for science, it’s even more important for the children. “We can’t waste early curiosity.”

“The fact that the infants can learn the vowels in utero means they are putting some pretty sophisticated brain centers to work, even before birth,” she said.